Interpretive Summary: The silverleaf whitefly is a major pest in vegetables, ornamentals and other economically important crops. Scientists at the USDA-ARS Center for Medical, Agricultural, and Veterinary Entomology in Gainesville Florida tested the effect of different plant combinations on th numbers of whiteflies and the numbers of whitefly eggs. Whitefly adult and egg counts were higher in squash and cantaloupes, and fewest in mustard. The other crops were intermediate. Repellent properties of mustard in the field did not effect attraction or egg-laying on other crops. Further field research needs to be conducted to determine if intercropping giant red mustard can be a promising strategy. However, squash and cantaloupe may have potential as “trap crops” to attract whitefly away from crops with higher economic value, or giant red mustard may be planted as a resistant crop when heavy whitefly infestations are expected.

Technical Abstract:
Different pairs of plants planted in a single pot were tested in the greenhouse for oviposition preference by the silverleaf whitefly (Bemisia argentifolii Bellows & Perring [Homoptera: Aleyrodidae]). Treatments consisted of the following in single pots: 2 giant red mustard plants (Brassica juncea (L.) Czern.), 2 collards (Brassica oleracea L. var. acephala) and 1 plant of each species. Treatments were exposed to whitefly adults. Numbers of eggs laid were counted after 6 d. Numbers of whitefly eggs were significantly lower on the mustard-mustard treatment. Average egg counts were lower on collard plants in the treatment where both host plants were presented simultaneously, than in treatments where collards were presented alone. These results suggest the possibility of repellent volatiles in the giant red mustard. To test for repellent effects in the field, an experimental plot was planted with squash (Cucurbita pepo L.), cabbage (Brassica oleracea L. var. capitata), broccoli (Brassica oleracea L. var. italica), collards, and cantaloupe (Cucumis melo L. reticulatus). A central plot of mustard transected the experimental area. To measure any effects of distance from the mustard, weekly sampling was performed at 5 equidistant intervals of 2.4 m to a distance of 12.2 m from the central mustard plot. The field experiment showed whitefly attraction to squash and cantaloupes and aversion to mustard, with other crops (including collards) with intermediate insect densities. Repellent properties of mustard in the field did not effect attraction or oviposition on other crops. It is possible that the sampling distances were too large to detect any repellent effects, or any effects of volatiles were stronger within the confines of the laboratory test arena. Further field research needs to be conducted to determine if intercropping giant red mustard can be a promising strategy. However, squash and cantaloupe may be have potential as trap crops for whitefly, or giant red mustard may be planted as a resistant crop when heavy whitefly infestations are anticipated.